The present invention is directed to products and methods having utility in medical applications. In one embodiment, the fibrous articles of the invention are polymeric membranes.
Electrospinning is a simple and low cost electrostatic self-assembly method capable of fabricating a large variety of fibers approximately 40 nm to 2 μm in diameter, in linear, 2-D and 3-D architecture. Electrospinning techniques have been available since the 1930's (U.S. Pat. No. 1,975,504). In the electrospinning process, there is a high voltage electric field between oppositely charged polymer fluid contained in a glass syringe with a capillary tip and a metallic collection target. As the voltage is increased to a critical value, the charge overcomes the surface tension of the suspended polymer cone formed on the capillary tip of the syringe of the glass pipette and a jet of ultrafine fibers is produced. As the charged fibers are sprayed, the solvent quickly evaporates and the fibers are accumulated randomly on the surface of the collection screen. This results in a nonwoven mesh of nano and micron scale fibers which has very large surface area to volume ratios and small pore sizes. Recently, electrospinning techniques have been developed and applied to the production of scaffolds in tissue engineering (Duan B, Yuan XY, et al. “A nanofibrous composite membrane of PLGA-chitosan/PVA was prepared by electrospinning”, European Polymer Journal 2006; 42: 2013-2022).
In the present invention, electrospinning is used to produce fibrous composite from biomaterials and keratins for fabrication of membranes or scaffolds for medical applications. Examples of biodegradable and/or bioabsorbable biomaterials include, but are not limited to, poly(lactic acid), poly(glycolic acid), poly(lactic-co-glycolic acid). Food and Drug Administration (FDA) have approved these polymers for some human clinical applications, such as surgical sutures and implantable devices. One of their potential advantages is that their degradation rate can be adjusted to match the rate of regeneration of the new tissue. They can keep the framework until the new tissue forms because of their sufficient mechanical strength. They can also be fabricated to be the same complicated shapes or structures as the tissues or organs to be replaced. However, these are still some disadvantages, such as hydrophobicity, the lack of cell-recognition signals. These results that no sufficient cell attach on the surface of these polymer materials. The interaction between the host environment and these biomaterials still has much potential for improvement. Keratins are the major structure fibrous proteins constructing hair, wool, nail and so on, which are characteristically abundant in cysteine residues (7-20 number % of the total amino acid residues). As alternative natural proteinous biomaterials for collagen, wool keratins have been demonstrated to be useful for fibroblasts and osteoblasts, owing to their cell adhesion sequences, arginine-glycine-aspartic acid (RGD) and leucine-aspartic acid-vlaine (LDV), biocompatibility for modification targets. Moreover, they are biodegradable in vitro (by trypsin) and in vivo (by subcutaneous embedding in mice). Keratin sponges with controlled pore size and porosity was fabricated by a compression-modeling/particulate-leaching method.
The fibrous composite of biopolymers and keratins could combine their advantages together and have potential medical applications.
It is an object of the present invention to overcome the disadvantages and problems in the prior art.